1. Field of the Invention
The present invention relates to a head mechanism control apparatus for controlling a head mechanism used for unloading from a recording medium a transducer head, a disk drive using the head mechanism control apparatus, and an unload control method for the transducer head in a disk drive, and particularly to a head mechanism control apparatus which can prevent mis-unloading in which unloading is terminated without the transducer head in the retract position.
2. Description of Related Art
In the load/unload mechanism, by moving a head arm having mounted thereon the head slider over a ramp provided in the vicinity of the inner periphery or the outer periphery of a disk, the head slider is unloaded to a retract position outside the disk, and the head slider is loaded over the disk by moving the head arm from the ramp. The head arm is mounted to a voice coil motor (VCM).
The head arm in the load/unload mechanism slides on the ramp surface in the unload direction to unload the head slider to the retract position, and it slides on the ramp surface in the load direction and away from the ramp surface to load the head slider over the disk. Further, the load/unload mechanism does not intentionally put the head slider in contact with the disk surface. The operation of such load/unload mechanism is controlled by the head mechanism control apparatus. The head mechanism control apparatus controls the drive current to be fed through the voice coil, thereby to perform the loading/unloading of the head slider.
Further, a latch mechanism is provided in the disk drive. The latch mechanism latches the head arm if a shock is applied to the disk drive when the head arm is at the retract position, thereby preventing the head arm from moving in the load direction and contacting the surface of the disk. The accidental contact of the head slider with the disk surface is called accidental landing. The disk surface is smooth, and if the accidental landing occurs, the disk surface may be scratched or the head slider may stick to the disk surface.
In the unload sequence of the above conventional head mechanism control apparatus, the sequence is ended when the control of the drive current for swinging the head arm in the unload direction is terminated. It is not verified that the head slider has been unloaded to the retract position. Mis-unloading can be caused due to a disturbance such as a shock during the execution of the unloading.
The mis-unloading can lead to accidental landing. If the head arm does not mount on the ramp and the head slider remains on the disk, the accidental landing is caused by a power save mode or the like when the rotation of the disk is stopped. Further, even if the head arm mounts on the ramp, a latch of the latch mechanism may not engage because the head arm has not returned to the retract position. If a shock is applied to the disk drive, the head arm can drop from the ramp to cause the accidental landing.
The present invention solves such problems of the background art, and its object is to provide a head mechanism control apparatus which can prevent mis-unloading.